Over 800,000 injuries to ligaments, tendons and the joint capsule occur every year in the U.S.A. While suturing is an alternative to treat ligaments'and tendons'injuries, it is not always successful because of the natural tissues'limited vascularization. As an option to this problem, grafts and prostheses are used to reconstruct these tissues. The Anterior Cruciate Ligament (ACL), an intra-articular ligament that contributes to the kinematics and stability of the knee, is commonly torn or ruptured in athletes and people practicing demanding activities. The approaches to ACL reconstruction include the use of autografts, allografts and prostheses, but these choices present shortcomings. In spite of these drawbacks, U.S. doctors performed an estimated 200,000 reconstructive surgeries in 2006. To overcome current limitations on treating ligament and tendon injuries like a torn ACL, the long term research objective of this proposal is to develop artificial ligaments and tendons that will mimic the properties of these human tissues. Since the mechanical properties of the materials selected to perform this project contrast significantly with those of the materials used in currently available prostheses, we expect to develop artificial ligaments and tendons with enhanced properties and closer resemblance to natural tissues. To achieve the long term research objective, three specific aims are proposed: 1) selection of polymers and investigation of the effect that secondary structures have on the properties of electrospun polymer nanofibers (EPN), 2) incorporation of carbon nanoparticles to the EPN to enhance their mechanical properties and 3) cell seeding to assess biological compatibility. These studies will investigate the electrospinning conditions of biocompatible polyurethanes to obtain micro- and nanofibers, which will be assembled into specific secondary structures to resemble ligaments and tendons. These assemblies will be extensively characterized, allowing us to design the targeted applications. Furthermore, carbon nanotubes and carbon nanofibers will be incorporated into the EPN to enhance the mechanical properties of the assemblies formed. Finally, studies on fibroblasts seeding and proliferation on the assemblies will examine the biological compatibility and potential for using the proposed structures as artificial ligaments and tendons. This project will investigate the hypothesis that certain synthetic polymers can be electrospun into micro- and nanofibers and assembled into specific secondary structures, which will possess mechanical properties similar to natural ligaments and tendons. Furthermore, we hypothesize that the mechanical properties of these secondary structures will be enhanced by incorporation of carbon nanoparticles. This project is innovative because it combines the use of certain polyurethanes (not explored for the proposed applications) through electrospinning to design prostheses. In addition to the unique combination of materials and technique proposed, the prosthetic ligaments and tendons targeted are potentially superior to the materials currently in use. PUBLIC HEALTH RELEVANCE: More than 800,000 injuries to ligaments, tendons and the joint capsule occur every year in the U.S.A., and many of these injuries require reconstructive surgery. The objective of this project is to develop artificial ligaments and tendons for potential prostheses, which could impact the public health.